Sorry, Jefti, even though your explanation of what ND's are and how light intensity is measured is fairly accurate, your suggestions for how to use them on your drone are not correct. A drone, or any other camera, does not need a filter to diminish the light level to make a good picture. In fact, it is usually the opposite with drones. You want shorter shutter speeds and be able to control a smaller aperture for greater depth of field. A lot of light provides you those opportunities. ND's have two basic purposes on a drone. By diminishing the light, you can achieve a shutter speed of 1/60, which is the generally recommended SS for capturing 4K video. Mid day light will often not allow you to get that setting even if you stop down the aperture to it's smallest size, which is not good for image quality. For still photography, you may want to capture a waterfall or river, and get that silky white effect that is done by using a longer shutter speeds such as 1/4 or 1/2 second, or longer. Again, you can not get that setting in regular daylight conditions. Using an ND will let you do that.
Using a CP on a drone is tricky and not always successful. CP filters work best when the direction you are facing the camera is 90 degrees to the light source. Keeping your axis near parallel to the light source will negate the effect of a CP, and you will lose around 1-1/3 stops of light for no gain (which is how much light a CP robs you of). And, those filters rotate one element of it's glass to adjust the effect. You can not do that while flying. And further, capturing wide angle images that include blue sky while using a CP will always give weird effects, as the amount of polarization will change from left to right as the angle of the light changes within the image. So your sky will be much darker on one end and gradually get lighter towards the other end of the sky. This always looks bad. Test this by looking thru a CP on a regular dslr camera and turn right and left. You will see this effect clearly.